Automatically acting fire protecting device for cinematographs



April 3, 1934. A. GRQTHE 1,953,600

AUTOMATICALLY ACTING FIRE PROTECTING DEVICE FOR CINEMATOGRAPHS Filed Aug. 25, 1931 Patented Apr. 3, 1934 UNITED STATES AUTOMATICALLY ACTING FIRE PROTECT- ING DEVICE FOR CINEMATOGRAPHS Alfred Grothe, Dulmen, Germany Application August 25, 1931, Serial No. 559,381 In Germany Hatch 10, 1931 6 Claims. (Cl. 88-17) Experience has shown that the easily infiammable material of the film strips in cinematographic projection apparatuses presents a continual source of danger. As the film strip in the picture window is subjected to the heat of the projection lamp, a danger of too strong heating during service exists at this point, as soon as the running of the film strip is checked or interrupted. This may occur either owing to failure in the drive of the feeding means for the film strip or owing to tearing of the latter.

As the film strip almost always consists of separate part-s stuck together, a tearing of the film must always be reckoned with at any time so that the absolutely automatic working apparatuses already produced by the development of technology in the cinematographic trade, nevertheless require continuous supervision. As soon as an interruption occurs in the feeding of the film strip, the drive must be disengaged by the person in charge. The infiammability of the film material is so great that, already in the case of the strip standing still in the film window for a second, the ignition of the strip occurs. This necessitates great care and rapid action on the part of the person in charge. In order to make the safety of the service practically independent of human cooperation, it has already been proposed to produce devices for preventing the heating of the film beyond the point of combustion, The objection to the known protecting devices consists in that they do not respond to all causes of interruption possible in the service of a cinematographic apparatus, but only become operative at a certain failure, for example, when the film tears above or in the picture window or below same. However, it is possible that the driving belt of the motor may tear or drop off which, as experience has proved, sometimes happens. In this instance therefore the protecting fiap arranged in front of the picture window in the beam passage and serving as fire protection, must be shut by the operator.

Devices have also been proposed for mechanically operating this protecting fiap. This fiap has for instance been made dependent upon the speed of the feed of the film band or, in the case of the tearing of the film band, an operation 01' the protecting flap has been effected by a feeler roller running on the film strip and adapted to release the protecting flap by contact by electrical means. These known protecting measures are themselves insufficient and open to the objection that their responding does not occur with the speed necessary for preventing infiagration of the film material.

The automatic protecting devices have evidently also the effect that thereby the attention of the operator is undoubtedly reduced. As 60 however the known devices make the cooperation of the operator necessary in the case of danger,

and the failure of the apparatus will be noticed by the operator only if be continually watches the same, the known devices do not meet the practical requirements to the desired extent.

The invention relates to a considerable improvement of the automatic fire protecting device in cinematographic apparatuses so that the protecting device becomes operative in the case of 1 any possible interruptions and that thereby the operators attention is drawn to the interruption in a conspicuous manner.

The feature of the invention consists in the arrangement of a device on the film strip above 1 the picture window, on the film strip below the picture window and on the driving belt, which, in case of failure occurring at the points in question, actuate a common element designed to eiiect the closing of the fire protecting fiap and of the s fire protecting channel on the rewinciing drum and the operation of an acoustic signal. The advantage is thus obtalned that in the case of any disturbances occurring in the service of the cinematograph, namely in the case of tearing u of a film above the picture window or below same, or in the case of tearing or falling off of the driving belt, the fire protecting fiap is instantaneously closed and the operators attention is attracted to the disturbance by an audible signal heard 90 from a distance. This latter is effected in dependency on a driving mechanism, which renders visible the position ready for use in a conspicuous manner by a pointer arrangement. A considerable advantage according to the invention consists in that the protecting device is composed of merely mechanically operating parts, in which sources of failure can never occur or are immediately perceivable.

The invention covers all sources of danger occurring in practice in cinematographs during service and brings the safety devices, provided at these points, into practical connection with a common actuating mechanism for the fire protecting fiap and for an acoustic signal, Thus, the guarantee is obtained that a fire cannot oc cur through the ignition of the film material, even if the apparatus is not under observation, as in the case of any failure occurring in the feeding of the film strip a safety device becomes opno erative, by means of which the protecting measures provided are rendered effective.

An embodiment of the invention is illustrated by way of example in the accompanying drawing in which:

Fig. 1 shows the entire arrangement in diagrammatic view. 7

1 Fig. 2 is,a rear elevation of the spring mechanism.

Fig. 3 is a detail.

Fig. 4 is a section through the spring mecha nism shown in Fig. 2.

1 designates the picture window, 2 the upper feed roll and 3 the film strip. The loop 4, formed by the film strip in front of the feed roll 2, is covered by a bow 5 in such a manner that one end of the bow is on the entrance point in the picture window, the other end being in front of the feed roll 2. The bow 5 is fixed on a two-armed lever 6, capable of oscillating freely around an axle 7, and on the second arm of which a counter weight 8 is fixed, which counterbalances the weight of the bow 5. An arm 9 is also provided on the lever 6 and serves as a locking element for the spring mechanism 10, or is connected with such an element. For this purpose the arm 9 is connected by means of a bolt 45 with one arm of a pawl 37, arranged in the casing of the spring mechanism 40 and engaging a ratchet wheel 38 connected to the spring axle 42 by toothed wheels 39, 40, 41.-

On an axle 11 of the spring mechanism 10, driven at high speed by toothed wheels 41 and 44, a wheel 12, an arm or the like, is keyed, which is provided with a pin 13 for engaging an intermediate element 15 leading to the protecting flap 14. The

pin 13 is arrested in the lower position by means of an abutment pin 17 in the spring mechanism casing, which pin comes in contact with an abutment pin 43 provided on the toothed wheel 41. Thus it is necessary to wind the spring mechanism, before the intermediate element of the flap can be hooked on to the pin 13. 'By means of a suitable coupling the complete running down and an overwinding of the spring mechanism is avoided.

fixed on the axle 11 of the wheel 12.

The arrangement and fixing of the bow 5, which surrounds the upper filmstrip 4, on the lever 6 which liberates the spring mechanism 10 is effected in such a manner that the position of the bow is adjustable relative to the lever. The means for the adjustable fixation of the bow may be arranged in any desired manner. Preferably a rack 18 fixed to the bow 5 is employed for this purpose and shiftably mounted in a head 19 of the lever 6, constructed as slide guide. A toothed wheel 20 mounted in the head 19 of the lever 6 engages in this rack, and its axle isprovided with an operating knob 22.

By turning'the toothed wheel 20 the position of the bow 5 relative to the lever 6 can be adjusted and adapted to the actual position of the film strip, so that the slightest alteration in shape of the loop causes a lifting of the bow 5 and consequently the actuation of the fire protecting device.

It is evident, that instead of the rack and pinion a screw spindle and nut may be employed for fixing and adjusting the bow 5.

The feeler roller 23 running on the lower portion of the film strip is mounted on a flap 24, which is arranged oscillatable around a bolt 25 on the apparatus in a suitable manner. The arrangement of the flap 24 is such that in lowered position it bears on to the fire protection channel 26 of the rewinding drum 2'7 and tightly closes same. On the flap 24 an abutment 28 is provided, which is situated within the range of an abutment 29 of the bar 8,'which serves as counter weight for the bow of the uper film safety device and is connected in the manner above described to the releasing lever of the spring mechanism eifecting the operation of the fire protecting fiap and of the alarm device.

In the case of tearing of the lower'film strip, the fire protecting channel of the rewinding drum is closed by the dropping flap, and at the same time also the fire protecting fiap is shut in front of the picture window, and the alarm device is actuated.

The moved parts of the projection apparatus are, as is known, actuated in common from an electric motor 30 by a driving belt 31. According to the invention a roller 32 runs on the belt 31 and is provided on an arm 33, keyed on a shaft 34. This shaft 34 is rotatably mounted on the apparatus in a suitable manner and extends from the belt side of the apparatus to the side on which the film strip runs. At this point a lever 35 is .mounted on the shaft 34 so that the end of this lever is situated within the range of an abutment 36 of the bar 8. I

The bar'8 is fixed on the operating-lever 6 of the spring mechanism 10. If the feeler roller 32 descends, the lever 35 bears against the abut.- ment 36 of the bar 8 and moves this bar, which in turn shifts the lever 6, which releases the spring mechanism, which actuates the fire. protecting flap 14 and a suitable alarm device.

I claim: 7

1. An automatic fire protecting device, comprising in combination with the upper film loop, the lower film strip and the driving belt of the apparatus, a clockwork having a spring mechanism constructed as alarm bell, a fire protecting flap adapted to be actuated by said mechanism, a rapidly rotatable axle in said spring mechanism, a wheel on said axle, a radially directed pin on the edge of said wheel, a cord holding said flap suspended on said pin, a second axle in said spring mechanism, a ratchet wheel on said second axle, a pawl engaging said ratchet wheel, a two-' armed lever carrying said pawl, a bow surrounding said upper film loop arranged on one arm of said lever,. feed rollers on said lower film strip, and a rodshaped weight fixed on the other arm of said lever extending within the .range of said rollers and said driving belt adapted to serve as common connecting" element between said feeler rollers and said lever.

2. An automatic fire protecting device for cinematographs as specified in claim 1, comprising in t combinationwith the upper film loop and the bow surrounding said film loop, catching grippers on said bow adapted to catch a torn end of said film strip.

matographs as specified in claim 1, comprising in combination with the film strip and the bow surrounding said strip, a rack fixed on said bow, an actuating lever, a head on said lever having 3. An automatic fire protecting device for cinea slide guide for said rack, an axle of said pinion, and an operating knob on said axle.

4. An automatic fire protecting device for cinematographs as specified in claim 1, comprising in combination with the spring mechanismand the axle of the wheel carrying the pin for suspending the cord for the protecting flap, an indicator visibly fixed on the front side of said spring mechanism.

5. An automatic fire protecting device for cine matographs as specified in claim 1, comprising in combination with the spring mechanism and the axle carrying the loose wheel with the pin, 

